1. Field of the Invention
The present invention relates to an optical pickup and an optical parts accommodation module for an optical pickup, suitably used in a disc player for recording onto and/or reproducing from a disc, such as a record medium for a CD (Compact Disc), a DVD or the like.
2. Description of the Related Art
The optical pickup apparatus for a disc player (the pickup apparatus being useful for reading and/or writing from/to a disc, such as for a CD or a DVD) may be standardized and slimmed through miniaturization. Such a miniaturized optical pickup apparatus can be used for various types of disc players.
The optical pickup apparatus equipped in a disc player is an apparatus for condensing a light beam, the light beam being emitted from a light emitting portion provided in the optical pickup apparatus onto an information recording surface of the disc (which is an information record medium), through an objective lens, to thereby optically record the information in a large data volume, as well as for collecting the reflected light from the disc irradiated with the light beam and then guiding the reflected light to a light receiving portion provided in the optical pickup apparatus, to thereby reproduce the record information.
In such a disc player, the disc is loaded on a turn table which is rotationally driven by a spindle motor, and, in case of recording the information onto or reproducing the recorded information from the disc, tracking control is performed such that the information reading light beam follows the information track on the disc, so as to permit the recording and/or reproduction of information.
Tracking control is performed as follows. Namely, the light beam emitted from the light emitting portion of the optical pickup apparatus is divided into one main beam and two sub beams, by a grating as one example of an optical element. Then, the two sub beams are irradiated onto the information recording surface in such a way that the two sub beams are inclined by a predetermined angle with respect to a tangential direction of the information track which the arrayed direction of the two sub beams is to follow. Then, the reflected lights from the information recording surface of the two sub beams are respectively detected by the light receiving portion of the optical pickup apparatus. Finally, by performing signal processing which obtains the difference between the outputs of those light receiving portions, control of the tracking direction at the time of recording or reproducing the information is achieved.
In this kind of optical pickup apparatus, errors of inaccuracy in assemblage/manufacturing, such as dimensional accuracy or the like, are inevitable at the time of assembling the optical parts. For instance, the arrayed direction of the two sub beams generated by the grating may be offset from the predetermined angle with respect to the tangential direction of the information track being followed, resulting in inaccurate tracking control performance.
In such an occurence, the rotation angle around the optical axis for the grating element in the optical pickup apparatus must be adjusted so as to compensate for the undesired offset, and an adjusting mechanism is therefore required. Further, a holding mechanism is also required so as to hold or maintain the condition of the grating, which has been mechanically adjusted. However, due to the slimming of the optical pickup apparatus as a result of miniaturization, it is difficult or even impossible to install an adjusting mechanism for mechanically rotating the grating element in the optical pickup apparatus.